salt flats mission

[big j]

is there anyway to change the timer for when the mission despawns.         i was  doing mission by myself yesterday and server pop was dead   and i went to clear it with 2 ai left and 10 more spawned in and killed me.  but as soon as i respawned the mission ended with alot of time and effort put into trying to do the mission      i know the old a2 missions you could set to once you attacked it stayed until either cleared or restart

p.s.  i was sniping    no vehicle used   cough cough